All humans are exposed to low levels of organochlorines, including pesticides (such as DDT). [unreadable] (1) We have continued to study the relationship of prenatal DDE exposure to anogenital distance (a sensitive measure of prenatal hormone exposure) in newborn boys in southern Mexico and published two papers this year. In animals, anogenital distance is a sensitive measure of prenatal hormone exposure. DDE, the most persistent DDT metabolite, has anti-androgenic properties, and exposure to DDE reduces anogenital distance in male rats. Anogenital distance has rarely been studied in humans, so we developed a standard protocol and assessed reliability of the measurements, finding that it could be measured more reliably than other measures in current use. We examined basic determinants of anogenital distance, including measures of overall body size such as birth weight. We have examined the relationship of DDE to anogenital distance.[unreadable] (2) Our previous work had shown that DDT may adversely affect lactation, shortening the duration of lactation, although the evidence on this point is still inconclusive. We are studying this question in the same Mexican population that is being examined for anogenital distance.[unreadable] (3) Previous work had shown a relationship of timing of menopause and DDE exposure. That study used postmenopausal samples to measure DDE; this is not optimal timing for measuring exposure. A new study has been done in mothers of a cohort of children we previously studied. Samples obtained from the mother around the time of childbirth were analyzed for DDE in the previous study. A questionnaire to assess menopausal status was administered. Data analysis is in progress.[unreadable] (4) In the menopause study, new blood samples were taken from a sample of study participants, and these have been analyzed for DDE and other organochlorines. We compared concentrations seen in these samples with concentrations seen in the samples taken approximately twenty years earlier to assess stability of concentrations over time and examine a few potential determinants of change.